In order to reduce the size and power of consumer electronics products, there is an effort to reduce the size and power of various integrated circuit devices incorporated in the consumer electronics products. In many circumstances, certain circuits may only be used once or infrequently. Even circuits that are not used frequently will not only unnecessarily take up space, but may draw power when not in use and therefore affect the efficiency of the consumer electronics product. Accordingly, it is important to efficiently implement circuits to reduce both the area occupied by certain circuits and the power consumed by those circuits.
Conventionally, a bipolar junction transistor (BJT) core is made up of a pair of BJTs which can either be identical (1:1) or of a fixed ratio (1:m). The BJT core difference output voltage (i.e. delta Vbe which is proportional to absolute temperature) is amplified using fixed gain ‘N’ based amplifier circuit. A generic analog-to-digital converter (ADC) measures this input temperature dependent voltage against the temperature independent reference voltage. Disadvantages of this arrangement for measuring temperature include that its gain is fixed irrespective of the input signal amplitude, it requires large area (due to the associated BJT matching requirement, an operation transconductance amplifier (OTA), and resistors involved in various signal conditioning), and it exhibits inaccuracies due to the associated circuit block that it drives. Since both the input temperature dependent voltage and the temperature independent reference voltage are required to be generated, it consumes both area and power.
Accordingly, circuits and methods that reduce the area and power used by an integrated circuit beneficial.